Evaluation and economics of shale gas reserves in the flysch-eocene formation of the Jaca basin

Resumen

Featured Application: The analysis through geological and geophysical techniques of shale gas fields with increased production rate through hydraulic fracturing stimulation, allows increasing national natural gas production and reducing external energy dependence. The new international outlook for the gas sector suggests evaluating exploitable reserves in previously unconsidered areas including hydraulic fracturing technology. In order to estimate the amount of gas in the Jaca Flysch formation, the analysis of geological and geophysical logs and the volumetric method have been used. It has been taking into account the part of the formation likely to contain gas, the porosity (2.65%) calculated from sonic logs with Wyllie’s equation, the water saturation (35.3%) with Archie’s formula, and the initial gas formation volume factor (Bgi), estimated with MHA-P3 software with the reservoir pressure/temperature data 3600 psi/90 °C. The economic analysis of each well has been carried out based on three options, without stimulation, with 50% and 100% stimulation by fracking, and five possible construction costs (7.5–15 MM€). The impact of the use of the fracking technology on the production of the well is about 48%. The production rate and the economic impact that its exploitation would have on the domestic demand for natural gas has been analyzed, resulting in a significant contribution to the national energy mix of between 10–20% of consumption for several years.